Conventionally known gas oil stocks include those manufactured by hydrorefining treatment or hydrodesulfurization treatment of straight-run gas oil obtained from atmospheric distillation of crude oil and straight-run kerosene obtained from atmospheric distillation of crude oil. Such gas oil stocks contain additives such as cetane number improvers and purification agents, which are used as necessary.
Incidentally, purification of diesel engine exhaust gas has been a goal in recent years from the viewpoint of improving the atmospheric environment and reducing environmental load. It has been attempted to achieve this goal by developing gas oil stocks that can reduce contaminants in diesel exhaust gas. For example, Patent document 1 below teaches that diesel particulate emission can be reduced by using a compression ignition engine fuel wherein the sulfur and aromatic compound contents and the ratio of isoparaffins and normal paraffins satisfy specific conditions.    [Patent document 1] Japanese Patent Application Laid-Open No. 2005-529213